1. Field of the Invention
The present invention relates to anti-viral and anti-tumor peptides and polypeptides.
2. Description of the Related Art
The transmission of HIV type 1 (HIV-1) from mother to fetus is rare during the first trimester of pregnancy when the secretion of human chorionic gonadotropin (hCG) is high in the placenta (De Rossi et al., 1992; Krivine et al., 1995). It was found that the β-subunit of hCG (hCGP), but not the α-subunit, is active against HIV-1 virus (Bourinbaiar et al., 1995) and AIDS-related Kaposi's sarcoma (Lunardi-Iskandar et al., 1995) in AIDS patients (Gill et al., 1996) and HIV-1 transgenic mice (De et al., 1997). These studies were conducted by using heterogeneous commercial preparations with different potencies reported for different source materials. There has been controversy as to whether the activity against Kaposi's sarcoma found in hCGP preparations is caused by hCGβ itself or other proteins (Griffiths et al., 1997; DeMarchi et al., 1997; Hopp et al., 1997; Flamand et al., 1998). Recently the present inventors reported their discovery that lysozyme contributes to the antiviral (anti-HIV-1) and anti-HHV8 activity of the β-core preparations of hCG.
Lysozymes are a family of enzymes that are widespread in nature. Hen egg-white lysozyme is a classic representative of this enzyme family, and the related enzymes found in birds and many other animals, such as mammals, reptiles and invertebrates are designated as chicken-type (c-type or conventional-type) lysozymes. Lysozyme was sequenced in the early 1960s and it was the first enzyme for which a complete X-ray crystallographic analysis was performed. All lysozymes have bactericidal activity and they all have muramidase activity which cleaves a β-glycosidic band between the C-1 of N-acetylmuramic acid and the C-4 of N-acetylglucosamine of peptidoglycan. The reference text, Lysozyme: Model Enzymes in Biochemistry and Biology, ed. P. Jolles, Birkhauser Verlag, Basel, Switzerland, 1996, provides a review of this family of enzymes. FIG. 1 on pages 10-11 of this text provides an alignment of the amino acid sequences of lysozymes from various organisms. In human lysozyme, the active site for muramidase activity resides in the cleft formed around residues Glu35 and Asp52.
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